Fix the definitions of get_cpu() and put_cpu().

They are supposed to disable preemption.

Reported by:	rstone
MFC after:	5 days

sys/compat/linuxkpi/common/include/asm/smp.h

@@ -38,11 +38,11 @@ int	linux_wbinvd_on_all_cpus(void);
 #endif
 
 #define	get_cpu() ({			\
-	sched_pin();			\
+	critical_enter();		\
 	PCPU_GET(cpuid);		\
 })
 
 #define	put_cpu()			\
-	sched_unpin()
+	critical_exit()
 
 #endif /* _ASM_SMP_H_ */